Heat exchange method and apparatus



y 1952 w. L. KAEHNI ET AL HEAT EXCHANGE METHOD AND APPARATUS 2SHEETS-SHEET 1 Filed July 15. 1947 V DIIIIBIIDIIDQDBDD lljl 1/ 1 l Tj q.

July 29, 1952 Filed July 15,

2 SHEETS-SHEET 2 I111 ///I l/ Ill/ll I l/ ll/I/l/I/ 0 a an 1 I I I 1 1 1i m H H 1 1 H I 1 1 1 I H H ,U H I 1 l I I I I 0 I I J U 1 1 1 J u 1 1 uI 1 H 1 1 1 H l I I H H n n I 1 1 H U 1 I I 1 1 1 u n r V FRANK J.KAEHNIPatented July 29, 1952 HEAT EXCHANGE METHOD AND APPARATUS William L.Kaehni and Frank J. Kaehni, Cleveland, Ohio, assignors to Metal CarbidesCorporation, Youngstown, Ohio, a corporation of Ohio Application July15, 1947, Serial No. 760,974

18 Claims. 1

The present invention relates to heat exchange methods and apparatusand, more particularly, to the use of an electrostatic field forincreasing the rate of heating or cooling of fluids and for increasingthe amount of heat transferable to or from the fluid under a given setof conditions.

We have found that by the use of an electrostatic field formed byelectrodes connected to a high potential unidirectional source ofelectrical energy the rate of transfer of heat from a solid body to afluid or from a fluid to a solid body or from one fluid to another fluidcan be appreciably increased and that the amount of heat transferablefrom one to the other under a given set of conditions can be increased.We have also found that by proper use and application of such anelectrostatic field the amount of heat which can be made available fortransfer to or from the solid body or fluid under certain circumstancescan be materially increased. As a consequence, processes and apparatusinvolving an exchange of heat can be simplified and the productivity orefficiencies thereof appreciably increased. Moreover, whereverdissipation of heat or transfer thereof from one fluid or solid body toanother is desired in order to obtain or maintain high operatingefliciencies, such, for example, as in the operation of motors,transformers, radio transmitting equipment, and the like, our inventionmay be utilized and appreciably improved results obtained.

In the heating of fluids such as-oils, water, other liquids, air andother gases, and in the cooling thereof, by the usual methods involvinga transfer of heat directly from the heating source or through someconvenient medium, the rate of heat transfer, as well as the totalavailable heat from the heating means employed, is quite important andin many industrial heat exchange installations these factors have beenof a limiting nature. In many instances these factors have made itnecessary to increase the total amount of equipment required forcarrying out a particular operation and have resulted in drasticallylimiting the capacity of the equipment. This is particularly true in theheating or cooling of those fluids, such as oil, which are not goodconductors of heat. This is also true where batch processes are employedfor heating fluids or solids which are in suspension or emulsion in afluid. Frequently it is necessary to utilize lengthy heating cycles orexpensive stirrers in such processes with the result that productioncosts are materially increased.

In many diiferent types of industrial apparatus the problem ofmaintaining parts or all of the apparatus at a proper operatingtemperature is quite acute. If not maintained at a proper temperature aloss of efliciency results. For example, electrical motors, transformersand generators must be cooled to prevent overheating with acorresponding loss in efliciency. Also, in radio transmittingequipmentit is desirable to cool the vacuum tube anodes to get bestresults. Gas turbines and internal combustion engines, likewise, must becooled to prevent general or localized overheating in use. We have foundthat, by the use of a unidirectional high potential electrostatic fieldin the manner more specifically described hereinafter in connection withheat exchange apparatus, cooling of such apparatus can be effected so asto maintain proper operating temperatures and, hence, greaterefficiency. In fact, in the case of electric motors, for example, webelieve that sufficient cooling can be obtained by the use of ourinvention to provide higher ratings for motors of any given size andcharacteristics.

In other types of industrial processes and equipment such as furnacesand other apparatus for annealing, normalizing or otherwise heattreating steels and other metals and apparatus for heating or coolingplastics and other materials, where it is necessary to put heat into orextract heat from a. liquid or solid, our invention also may be utilizedwith the result that the heating or cooling can be accomplished moreefficiently and more effectively.

In view of the limitations imposed by low heat transfer on variousindustrial processes and equipment involving an exchange of heat betweenfluids or between a fluid and a solid body or between solid bodies,various efforts have been made to increase the rate of heat exchange aswell as the total heat transferred and many expedients have beenadopted. In this connection, the prior workers have followed the more orless conventional practices. However, the present invention constitutesa completely new approach to the problem of heat transfer. It providesfor an induced electro-motion within the fluid constituting one of theelements of the heat ex change system. I

In accordance with our invention, we apply an electrostatic field to afluid in the heat exchange system while the fluid is being heated orcooled. The fluid may be the medium to be heated or cooled or it may bemerely the transfer medium for effecting a transfer of heat between twoor more solid bodies or between a solid body and another fluid.

By applying an electrostatic field to the fluid while it is being heatedor cooled or acting as a transfer medium, a continuous motion of chargedparticles, molecules or atoms from a surface of one polarity through thefluid to a surface of opposite polarity is provided. A unidirectionalcurrent, preferably ordinary direct current, of high potential is usedto create the electrostatic field between suitably positionedelectrodes. In some applications of our invention one or both of theelectrodes may be separate parts of the apparatus; but in mostapplications one or both of the spaced electrodes for providing theunidirectional electrostatic field constitute a part or parts of theapparatus utilized for heating, cooling, carrying, conducting orsupporting the fluid.

By the use of a unidirectional high potential the particles, moleculesor atoms are moved between the electrodes. They may move the entiredistance from one electrode to the other or they may move only a part ofthe distance, depending on the extent of the movement required to obtainand give up their charges. This not only provides a more rapid and agreater heat exchange but also provides a more rapid equalization of thetemperature of the fluid body itself.

In view of this charging of the particles of the fluid and the resultantelectro-motion between the electrodes our invention may be used toadvantage where a mixing of hot and cold fluids or a mixing of fluids atthe same temperature is desired. It may also be applied in the making ofemulsions, solutions or suspensions of liquids and solids.

Where our invention is applied to the heating of a dielectric fluid,such as oil, air, gases of various types, kerosene, alcohol, resins andfluid plastics flowing through a chamber, such as a tube, theelectrostatic field may be applied in such a way that the heatingmember, which may be a heated surface or a heated wire, forms one of theelectrodes, the other electrode being positioned with respect to thefluid so that the electrostatic field Will traverse the fluid itself.Likewise, in the cooling of such fluids the surface or member to whichthe fluid is to give up its heat may be one of the electrodes and theother electrode may be placed in such a way with respect to the fluidthat the electrostatic field will traverse it and impart what we call anelectro-motion to the particles, etc. However, we have found that anincrease in the rate of heating or cooling of the fluids by thiselectrostatic means can be accomplished, even though the heating orcooling element or surface is not used as one of the electrodes for theestablishment of the electrostatic field. For example, where a fluid isbeing heated by contact with a heating element or surface, theelectrodes can be spaced within the fluid and the heating or coolingmeans positioned between the electrodes so that the electro-motionimparted to the particles, molecules or atoms of the fluid will causethem to move from the one electrode to the other and in the course ofsaid movement come in contact with or in close proximity to the heatingor cooling means. However, best results are obtained where the heatingor cooling surface or element is one of the electrodes for forming theelectrostatic field.

By way of illustration, our invention can be readily applied to theheating of oils and the like as they pass through suitable conduits. Aresistance wire extending longitudinally through the tube carrying thefluid can be used for heating it as it moves through the tube. This wiremay be an ordinary Nichrome resistance wire and may be connected to asource of alternating current for supplying the heat. If the conduit ortube is of metal or some other electrically conductive material, it maybe utilized as one of the electrodes and the heated wire for supplyingthe heat to the fluid can be utilized as the other electrode. However,if the conduit or tube containing the fluid is relativelynon-conductive, the resistance wire can still be used as the oneelectrode and a metal electrode on the inner periphery of the tube orconduit can be utilize as the other electrode. As the oil or other fluidpasses through the tube, it is heated by the resistance element.

When the electrostatic field is applied in the manner just mentioned,the rate of heat transfer from the heating element to the fluid isappreciably increased, the increase in many instances being as high as1100%. Moreover, the oil or other fluid is heated more uniformly, due tothe electro-motion imparted to the fluid by the electrostatic field. Inother apparatus illustrated diagrammatically herein, similar increasesin the rate of heat exchange have been obtained. In addition, we haveobtained an increase of from 40-80% in the total amount of heattransferred.

While, as stated above, it is not necessary that the resistance wireforming the heating element be utilized as one of the electrodes, wehave found that it is desirable to use it as an electrode whereverpossible because a greater increase in heat transfer can be obtainedthan when separate, spaced electrodes, which form no part of the regularheat exchange system, are used. Moreover, due to the fact that there isa greatly increased rate of heat transfer from the heating element anappreciably greater amount of current can be supplied to the resistanceheating element. In other words, the current carrying capacity of agiven heating element is appreciably increased as a result of theincreased rate of heat exchange.

By the use of our invention the rate of heat transfer as well as theamount of heat which can be obtained from a surface at a giventemperature can be increased. In other words, where an electrostaticfield is used the amount of heat transferable, as well as the rate oftransfer from a surface of a given temperature, can be increased. Thispermits. the operation of various types of apparatus at lowertemperatures without any sacrifice in the heat transferred. Anotheradvantage arising out of our invention is that the transfer of heat canbe controlled or regulated by merely changing the voltages employed.

Although our invention is especially useful in processes involving heattransfer, it will be apparent from what has already been stated that itis not limited thereto and may be utilized where uniformity oftemperature in or mixing of a fluid body is desired. The application ofa direct current high potential to the fluid moves the particles fromadjacent the one electrode to a point adjacent the other electrode, andthis continuous motion of the charged particles mixes the fluidthoroughly.

While the specific illustration of our invention set forth above relatesto a heating operation,

our invention is not limited thereto but may be used where cooling isdesired. The increased heat transfer provided by our invention makes itpossible to electrostatically cool a gas or a solid body and, hence, ourinvention can be used where the primary objective to be accomplished isthe cooling of a fluid or a solid body as distinguished from those heatexchange processes in which the primary objective is the heating of afluid or a solid; Furthermore, our invention is not limited to processesand apparatus wherein the heat is applied electrically but may be usedin heating operations where the heat is supplied by other means such asby combustion of fuels or by preheating of a fluid or solid prior to theapplication of the electrostatic field.

Nor is our invention limited to processes and apparatus wherein thechamber, solid body, or conduit carrying or contacting the fluid is anelectrical conductor; The chamber, solid body, conduit, etc. contactingthe fluid may be a dielectric material, such as glass. The fluidutilized, however, must have sufiicient dielectric properties to permitthe establishment of an electrostatic field therein.

In the accompanying drawings, we have shown diagrammatically, forpurposes of illustration only, several ways in which our invention maybe utilized.

In the drawings:

Figure 1 is a vertical section through apparatus which may be used forheating a body of liquid;

Figure 2 is a vertical diametral section through apparatus whichalso maybe used for the heating of a body of liquid;

Figure 3 is a diagrammatic sectional viewshowing the manner in which ourinvention may be utilized in the heating of a fluid during its passagethrough a tube;

Figure 4 is a diagrammatic sectional view showing another way in whichour invention may be applied to the heating of a fluid during itscontinuous passage through a tubular chamber;

Figure 5 is a diagrammatic sectional view showing another way in whichour invention may be applied to the heating of a fluid as it passesthrough a tubular chamber;

Figure 6 is a sectional View taken along the line VI-VI of Figure 5; t

Figure '7 is a diagrammatic sectional view showing another way in whichour invention may be applied to the heating of a batch of fluid in acontainer;

Figure 8 is a diagrammatic sectional view illustrating the applicationof our invention to a process which involves the heating of one fluid asit passes through a tube or the like, and also the transfer of heat fromthat fluid through a solid body to another fluid;

Figure 9 is a view partly in section and partly in elevation showing theapplication of our invention applied to the heating of a fluid by meansof a series of fuel burners as the fluid is passed through a tube; and

Figure 10 is a section taken along the line X-X of Figure 9.

In the embodiment diagrammatically illustrated in Figure 1, the liquid 2is contained in a chamber 3, which is open at the top and closed at thebottom. This container is made of glass, although, as will be apparent,it can be made from any suitable material since the container itselfdoes not form one of the electrodes. The

heat for heating the liquid is applied through an electric resistanceheater 4 which extends upwardly through the bottom of the containerthrough the bushed opening 5. The leads 6 which are connected to theheater are suitably connected to a heating current which, in generalwill be alternating current. The electrostatic field in this embodimentis applied to the liquid by utilizing the resistance heater 4, which ispreferably metal, as one of the electrodes and a metal thermometer tubeI as the other electrode. This metal thermometer tube 1 extends upwardlythrough the bottom of the container through the hushed opening 8. Theleads 9 which are connected to the electrodes are connected at theirother ends to a source of high potential direct current. In the drawingthe heater is illustrated as the positive electrode, although it isimmaterial whether this heater or the thermometer tube is the positiveelectrode. The thermometer tube 1 is of metal and is connected by aconduit Hi to an indicating member ll so that the increase in thetemperature of the liquid can be determined readily. I

The liquid to be heated in this embodiment may be oil, alcohol,turpentine, glycerine, paraffine, various petroleum products, linseedoil, shellac, varnish, or any other liquid having dielectriccharacteristics.

The embodiment illustrated in Figure 2 is likewise suitable for batchheating a liquid. The chamber I5, in which the liquid 2 is heated, is ofa metal having electrical conductivity. The heat for raising thetemperature of the liquid is provided by a resistance element 1-6 whichsurrounds the side wall of the container. The resistance element I6 isconnected by suitable leads I! to a source of heating current, which maybe either alternating or direct current. The container itself forms oneof the electrodes for impressing an electrostatic field on the liquid.The

other electrode in this embodiment is a metal thermometer bulb I 8'which extends into the liquid through a bushed opening iii in the bottomthereof. The container and the metal tube are connected b leads 20 to asuitable unidirectional high potential electric source. In order todetermine the extent to which the liquid is heated, an indicator 2| isprovided for the thermometer and it is connected to the thermometer bulbby the conduit 22. The thermometer employed is the ordinary commercialliquid-type thermometer. In this embodiment, the high potentialelectrostatic field causes the particles of the fluid to be charged andto pass back and forth between the positive and negative electrodes,with the result that the rate of heating is materially increased. Also,the equalized ultimate temperature is higher when the electrostaticfield is impressed on the liquid than when the heating current alone isemployed.

The embodiment in Figure 3 diagrammatically illustrates the applicationof our invention to a process in which a fluid, which may be air or gasor any other dielectric, passes continuously through a tube or othersuitable enclosure. In this embodiment, the fluid passes through thetube 25. A heating wire 26 extends axially through the tube and is incontact with the fluid. The heating wire is preferably a rela-- tivelyflat Nichrome wire, although, as will be apparent, any other suitableelectric resistance elementmay be employed. This wire is connected byleads 2! to a source of alternating current. The tube 25, inthisembodiment, is metal 7 and is one of the electrodes in the electrostaticfield. The other electrode is the wire 26 which, as stated, alsofunctions as the resistance heater. The tube 25 and the Wire 26 areconnected by leads 28 and 29, respectively, to a unidirectional sourceof high potential.

The embodiment shown in Figure 4 is likewise suitable for the heating ofa dielectric fluid as it passes continuously along the source of heat.In this embodiment, the fluid passes through the tubular chamber 30,which is preferably of metal, and it is heated by the resistance heatingelement 3| which extends spirally around the outer periphery of thetube. The heating element is connected b leads 32 to a source ofalternating current. As in the embodiment shown in Figure 3, the sidewall of the chamber itself forms one of the electrodes. In thisembodiment, the tube 3!] is connected by a lead 33 to the positive sideof a source of unidirectional current of high potential, while in Figure3, the metal tube 25 is illustrated as being connected to the negativeside of the high potential source. .As is stated above, equally oodresults are obtained, irrespective of polarity, but a unidirectionalcurrent, as distinguished from an alternating current, is required.

In Figure 4 the negative side of the high potential source is connectedby a lead 34 to a longitudinally extending electrode 35 positionedaxially of the tube. This electrode is in the form of a relatively flatNichrome wire. Round wire may be used, but we have found that somewhatbetter results are obtained where a flat wire with rounded edges isused.

The embodiment shown in Figures and 6 is likewise suited for the heatingof a continuously moving dielectric fluid. The fluid passes through thetubular chamber 40 which may be of metal or a dielectric, such as glass.The source of heat is a longitudinally extending wire 4| which extendsaxially of the tubular container. The wire is connected to a source ofalternating current by means of leads 42.

In this embodiment, neither the tube nor the heated wire 4| is anelectrode in the electrostatic field. Spaced electrodes 53 and 44 areprovided within the tube 40. Any suitable form of electrode which is incontact with the fluid may be used but, as is illustrated, where thechamber is in the form of a cylinder, the electrodes are preferably inthe form of curved plates positioned on opposite sides of the tube. Theelectrodes should be positioned so that charged particles in passingfrom one electrode to the other will come in contact with or in closeproximity to the source of heat. The electrodes are connected to asuitable unidirectional high potential current by leads 45.

The embodiment shown in Figure '7 is for batch heating of a dielectricfluid. In this embodiment, the chamber containing the liquid is in theform of a tube 50 which is open at the upper end and which is closed atthe lower end by a stopper 5|. The heat for heating the fluid issupplied by means of a resistance element 52 which extends verticallythrough the chamber. At its upper end the heating element 52 isconnected to a lead 53 which is connected to one side of a source ofalternating current. The lower end of the resistance element isconnected by a suitable lead 54 to the other side of the alternatingcurrent source. The stopper 5! is preferably made of an insulatingmaterial, such as rubber, and the resistance element passes through anopening 55 which extends through the stopper. The container may be ofmetal or any suitable substance, since it does not form one of theelectrodes in this embodiment. The electrodes are the resistance heatingelement 52 and a metal tube 56 which is of a smaller diameter than thetube 58, but which nevertheless closely approximates the diameter of thetube 50. This metal tubular electrode and the resistance element areconnected to a unidirectional high potential source by leads 5'! and 58,respectively.

In the embodiment shown in Figure 8, several heat transfers areefiected. A resistance element 60 extends axially of a tube Bl throughwhich a fluid may be passed in the direction of the arrow. An outer tube62 surrounds the tube 6! and provides a chamber for a fluid passingtherethrough in the same direction as or the opposite direction to thefluid in the pipe 6|. In order to increase the rate of heat exchangebetween the resistance element 88 and the fluid passing through the tubeEl, the heating element 653 forms one electrode and the tube itselfforms the other. The wire 60 and the tube 61 are connected to a sourceof direct current through leads 63. Where it is desired to increase therate of heat transfer between the tube 5! and the fluid passing betweenit and the tube 62, the tube 62 can be connected by a lead 54 to oneside of a source of unidirectional high potential current, so that thetube 6| and the tube 62 will each form an electrode for an electrostaticfield impressed on the fluid passin through the tube 62. As isillustrated in the drawing, in an embodiment of this character the outertube and the resistance heating element should be of the same polarity,the tube Bi being of opposite polarity.

As will be apparent, the inner tube 5! of this illustrative embodimentmay be heated in various ways. For example, instead of heatin it byelectrically heating the fluid passing through it, the fluid may beheated before entering the tube 6|. In passing through the tube it willgive up its heat to the tube which in turn will heat the fluid withinthe outer tube or chamber 52 and that fluid may give up its heat to theouter tube or to anything positioned within that tube or chamber. Inthis way, our invention may be applied to the ordinary tube typeannealing or heat treating furnace for treating metal sheets or the likeplaced therein.

The embodiment of our invention shown in Figures 9 and 10 illustratesour invention as applied to a heating operation in which heat issupplied by gas or other fuel burners. The tube ll carries the fluid tobe heated and is surrounded by one or more circular burners 12 havinsmall ports 53 spaced around the inner periphery thereof. Gas or othersuitable fuel is supplied to each burner 12 by an inlet M. The wire orrod extending through the tube forms one electrode and is connected by alead 76 to the positive side of the source of high potential. The tubeforms the other electrode and is connected by a lead 11 to the negativeside of the high potential source. If desired the burners also may beconnected to the positive side of the high potential source. In this wayan electrostatic field is established through the fluid passing throughthe tube and one is established between the flames and the tube. Bothfields increase the amount of heat transferred and the rate of transfer.

Where our invention is employed the increase in heat, exchange isgreatest when the distance between the oppositely charged surfaces issmall, such as, for example, from a fraction of an inch to'severalinches, although a greater spacing of the electrodes may be employedwith effective results. However, under such circumstances, higher directcurrent potentials are required in order to get the best results.Voltages of from 5,000 to 20,000 produce excellent results on mediumsized tubing of two to three inches in diameter. It will be understood,however, that any suitable voltages can be utilized, depending on thenature of the apparatus to which the invention is applied.

By the term high potential as used herein, we mean potentials of theorder of those normally used for the creation and maintenance ofelectrostatic fields and, more specifically, a potential in excess ofabout 1500 volts per inch of spacing between the electrodes utilized forforming the field. With potentials of this magnitude, advantageousresults can be obtained, whereas with potentials of low magnitude noeffective results can be obtained.

The increase in rate of heat transfer obtainable by our invention, ofcourse, will depend upon the conditions under which it is used. We havefound, for example, that we can step up the rate of heat transfer inapparatus of the character described above to 1100%, depending on theconditions employed.

While we have described and diagrammatically illustrated severalembodiments of our invention, it will be readily apparent to thoseskilled in this art that it may be utilized for (a) heating or coolingof fluids and solid bodies in heat .exchangeprocesses and apparatus, (b)cooling motors, generators, transformers, gas turbines, internalcombustion and other types of engines and the like, cooling vacuum tubeanodes and other parts of radio transmitting equipment, (d) heating orcooling metals, plastics and other materials in annealing, normalizing,heat treating, melting, and other types of heating furnaces or chambers,(e) refrigerating apparatus, (f) mixing various types of fluids ormixing fluids and finely divided materials, and (g) for coolinglubricating oils for engines such as those in ships where special marinecoolers are now required. It may be employed or embodied in this andvarious other ways within the scope of the appended claims.

In our copending application, Serial No. 641,398, filed January 15,1946, we have described and claimed the use of an electrostatic field inconnection with heating methods and apparatus and, more particularly, inconnection with flames, electric arcs and other heat generating media.The present application is related to said copending application and, inrespect of the broad general disclosure of said application, may beconsidered as a continuation-in-part thereof.

We claim:

1. The method of effecting an exchange of heat between two bodies, atleast one of which is a dielectric fluid, which comprises bringing thefluid into contact with the other body when they are at differenttemperatures and with at least one electrode adapted when charged tomaintain a high potential unidirectional electrostatic field through thefluid while it is in contact with the other body, said field having apotential gradient in the fluid in excess of about 1500 volts per inch,and maintaining said field through the fluid while it is in contact withthe other body.

10 2. The method of effecting an exchange of heat between two bodies, atleast one of which is a dielectric fluid, which comprises bringing thefluid into contact with the other body when they are at differenttemperatures and with an electrode, and maintaining a high potentialunidirectional electrostatic field through the fluid and between saidother body and said electrode while the fluid is in contact with saidother body and said electrode, said field having a potential gradient inthe fluid in excess of about 1500 volts per inch.

3. The method of effecting an exchange of heat between two bodies, atleast one of which is a dielectric fluid, which comprises bringing thefluid into contact with the other body when they are at differenttemperatures and with at least two electrodes adapted to maintain anelectrostatic field through the fluid when it is in contact with theother body and maintaining a high potential unidirectional electrostaticfield between .the electrodes and through the fluid when it is incontact with said other body, said field having a potential gradient inthe fluid inexcess of about 1500 volts per inch. I

4. The methodof efiecting an exchange of heat between a solid body andadielectric fluid which comprises bringing the fluid into contact withthe body when they are at different temperatures and with at least oneelectrode adapted when charged to maintain a high potentialunidirectional electrostatic field through the fluid when it is incontact with the solid body and maintaining said field through the fluidwhile it is in contact with the solid body, said field having apotential gradient in the fluid inexcess of about 1500 volts per inch.

5. The method of effecting an exchange of heat between an object and adielectric fluid which comprises bringing the fluid into contact withthe object when they are at different temperatures and an electrodespaced from, the object and maintaining a high potential unidirectionalelectrostatic field through the fluid and between the object and theelectrode, said field having a potential gradient in the fluid in excessof about 1500 volts per inch.

6. The method of effecting an exchange-of heat between an object and adielectric fluid which comprises heating the object, bringing the fluidinto contact with and passing it over both the object and an electrodespaced from the object and maintaining a high potential unidirectionalelectrostatic field through the fluid and between the object and theelectrode, said field having a potential gradient in the fluid in excessof about 1500 volts per inch.

'7. A method of heating a dielectric fluid which comprises passing thefluid in contact with a heated surface and with at least one electrodespaced from said surface and adapted when charged to maintain a highpotential unidirectional electrostatic field .through said fluid andsubjecting the fluid to such a field while it is in contact with saidsurface and said electrode, said field having a potential gradient inthe fluid in excess of about 1500 volts per inch.

8. A method of heating a dielectric fluid which comprises the steps ofpassing the fluid in contact with a heated surface and with an electrodespaced from said surface and subjecting the fluid as it passes incontact with said surface and said electrode to a high potentialunidirectional electrostatic field between the heated surface and saidelectrode, said field having a potential 11 gradient in the fluid inexcess of about 1500 volts per inch.

9. A method of heating a dielectric fluid which comprises passing thefluid in contact with a heated surface and with at least one electrodespaced from said surface and adapted when charged to maintain a highpotential unidirectional electrostatic field through said fluid andsubjecting the fluid to such a field while it is in contact with saidsurface, said field having a potential gradient in excess of about 1500volts per inch.

10. The method of increasing the heat transfer between a solid and adielectric fluid which comprises bringing the fluid into Contact withthe solid when they are at different temperatures, establishing anelectrostatic field, by means of a high potential unidirectional source,between the solid and an electrode in contact with the fluid, said fieldhaving a potential gradient in excess of about 1500 volts per inch.

11. The method of increasing the heat transfer between a solid and adielectric fluid which comprises bringing the fluid into contact withsaid solid when they are at different temperatures and at least twoelectrodes spaced from and on opposite sides of said solid andmaintaining a high potential unidirectional electrostatic field throughsaid fluid between said electrodes, said field having a potentialgradient in excess of about 1500 volts per inch.

12. Apparatus for exchanging heat between a dielectric fluid and acontainer therefor comprising a casing at a temperature difierent fromthe temperature of the fluid and adapted to contain said fluid and toserve as one electrode in a high potential electric circuit, a secondelectrode in said casing and spaced therefrom, and means for maintaininga high potential unidirectional electrostatic field between saidelectrodes, said field having a potential gradient in excess of about1500 volts per inch.

13. Apparatus for exchanging heat between a dielectric fluid and acontainer therefor comprising a casing at a temperature different fromthe temperature of the fluid and adapted to contain said fluid and toserve as an electrode in a high potential circuit, a second electrode insaid casing and spaced therefrom, and means including said electrodesfor establishing a unidirectional high potential electric field throughthe fluid having a potential gradient in excess of about 1500 volts perinch.

14. Apparatus for the exchange of heat between two dielectric fluidshaving different temperatures comprising two casings, one positionedwithin the other and each adapted to contain one of the fluids and meansfor establishing a high potential unidirectional electric field betweenthe two casings, said field having a potential gradient in excess ofabout 1500 volts per inch.

15. Apparatus for the exchange of heat between two dielectric fluidshaving diiferent tem- 12 peratures comprising two casings, onepositioned within the other and each adapted to contain one of thefluids, an electrode within the inner casing and means for establishinghigh potential unidirectional electric fields of potentials in excess ofabout 1500 volts per inch between the electrode and the inner casing andbetween the two casings.

16. The method of effecting an exchange of heat between a solid objectand a dielectric fluid, which comprises passing the dielectric fluidwhen at a different temperature than the solid along and in contact withthe solid object and an electrode spaced from the object, andmaintaining a high potential unidirectional electrostatic fleld throughthe fluid between the object and the electrode, said field having apotential gradient in the fluid in excess of approximately 1500 voltsper inch.

17. In the method of controlling the flow of heated media between a heatsource and an adjacent body, the steps comprising providing a heatsource and establishing and maintaining an electrostatic field having apotential gradient in excess of about 1500 volts per inch between theheat source and the adjacent body to which heat is to be applied whileusing the heat source as the positive electrode for creating theelectrostatic field.

18. In the method of controlling the flow of heat between a heat sourceand an adjacent body, the steps comprising providing a source of heatand establishing and maintaining a low energy unidirectionalelectrostatic field having a potential gradient in excess of about 1500volts per inch between the heat source and the adjacent body while usingthe heat source as the positive electrode for establishing theelectrostatic field, said field being of such character that no currentexcept that incident to the maintenance of the field passes between theheat source and said body.

WILLIAM L. KAEHNI. FRANK J. KAEHNI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 732,616 Burgess June 30, 19031,473,347 Hoskins Nov. 6, 1923 1,835,557 Burke Dec. 8, 1931 1,854,475Littlefleld Apr. 19, 1932 1,980,521 Hahn Nov. 13, 1934 1,980,821 PalueifNov. 13, 1934 2,018,434 Ballentine Oct. 22, 1935 2,264,495 Wilner Dec.2, 1941 2,362,889 Darrah Nov. 14, 1944 FOREIGN PATENTS Number CountryDate 429,352 Great Britain May 28, 1935

